5alpha-Androstenone concentrations in sow plasma during the estrous cycle

Plasma concentrations of 5alpha-androst-16-en-3-one (5alpha-androstenone), the steroid responsible for boar taint, were measured by radioimmuno-assay in eight sows during the estrous cycle. The steroid concentrations ranged from a low of approximately 500 pg/ml to a high of 2.2 ng/ml during the estrous cycle. Noticeable features in the hormone profile of sows sampled, were the decline in the period preceding estrus, comparatively low levels at estrus and an increase post-estrous. Changes in hormone concentrations over the estrous cycle were significant (P<.05). The timing of the changes in 5alpha-androstenone concentrations during the period preceding estrus among the sows studied was not consistent. The physiological significance of the changes in 5alpha-androstenone concentrations during the period preceding estrus among the sows studied was not consistent. The physiological significance of these changes in 5alpha-androstenone concentration seen during the estrous cycle is not clear. Any bearing these changes may have on the malefemale sexual relationship in pigs needs to be further investigated in view of the known pheromonal function of 5alpha-androstenone.     

Genomic fluidity and pathogenic bacteria: applications in diagnostics, epidemiology and intervention

The increasing availability of DNA-sequence information for multiple pathogenic and non-pathogenic variants of individual bacterial species has indicated that both DNA acquisition and genome reduction have important roles in genome evolution. Such genomic fluidity, which is found in human pathogens such as Escherichia coli, Helicobacter pylori and Mycobacterium tuberculosis, has important consequences for the clinical management of the diseases that are caused by these pathogens and for the development of diagnostics and new molecular epidemiological methods.     

Distribution of legionellae in a hospital water system: prevalence of immunologically and genetically related Legionella pneumophila serogroup 6 isolates

A hospital warm water system was monitored for the presence and distribution of legionellae. Subtyping of ten selected Legionella pneumophila isolates, originating from four different sites in the system by using serogroup specific antisera in an indirect immunofluorescence test, revealed that nine of the ten isolates belong to serogroup 6, while the remaining one was serogroup 10. Two monoclonal antibodies (mAbs) specific for a subgroup of serogroup 6 strains were further used for characterization. None of the strains reacted with these mAbs. Genome analysis by elaborating NotI profiles using the pulsed field gel electrophoresis (PFGE) technique revealed that nearly all serogroup 6 isolates derived from different sites, including a new building connected by a ring pipe, were identical according to restriction fragment patterns. The patterns were distinguishable from those of the two L. pneumophila serogroup 6 reference strains, and from that of the L. pneumophila serogroup 10 isolate. These data argue for a relatively homogeneous L. pneumophila serogroup 6 population in the entire water system.     

Common molecular mechanisms of symbiosis and pathogenesis

Traditionally, symbiotic and pathogenic interactions were considered different manifestations of the bacteria-host interaction. However, the molecular mechanisms that mediate communication between and cellular modulation of the involved partners are quite similar. With this review we aim to contribute to a reduction of the traditional gap between symbiosis and pathogenesis research.     

Oral vaccination of rats with live avirulent Salmonella derivatives expressing adhesive fimbrial antigens of uropathogenic Escherichia coli

Abstract The avirulent Salmonella typhimurium F885 was transformed with a plasmid carrying the cloned S fimbriae genes of a uropathogenic Escherichia coli . The resulting transformant (F885-1) produced efficiently E. coli S fimbriae and was used for live oral vaccination of rats. For comparison rats were immunized subcutaneously with isolated S fimbriae. Both routes of vaccination resulted in a significant IgG antibody response to S fimbriae. In addition live oral vaccination induced a serum IgA response against S fimbriae. After transurethral infection of rats with a S fimbriae producing E. coli a 10-fold reduction of bacterial counts in the kidney was observed in rats orally vaccinated with F885-1 as compared to unvaccinated controls. This study suggests that the avirulent Salmonella F885 may be used as a fimbrial antigen carrier for oral vaccination against renal infections.     

Altered enzyme expression in propylnitrosamine-induced Syrian hamster lung lesions

Focal proliferative and neoplastic lung lesions induced in Syrian hamsters by dihydroxy-di-n-propylnitrosamine (DHPN) were investigated using a combined histochemical, autoradiographic and electron microscopic approach. Expression of elevated glucose-6-phosphate dehydrogenase (G6PD) and gammaglutamyl-transpeptidase (GGT) activities and levels of immunohistochemically demonstrable glutathione S-transferase placental form (GST-P) were evident in epithelial cells of focal proliferative populations and bronchioloalveolar neoplasms. Binding for the GST-C form, normally only weak, became very pronounced in the stromal elements of DHPN-induced lesions. Increased labelling with tritiated thymidine was associated with increase in morphological atypia within the tumours. Although the enzyme phenotype findings were equivocal the presence of lamellar bodies in some cells of focal proliferative and neoplastic lesions suggested an origin from alveolar type II cells. The present results regarding changed enzyme phenotype in lung lesions suggest important similarities at the biochemical level for the process of neoplasia in the different target organs of DHPN in the hamster and indicate that GST-P may be a useful 'marker' for lung neoplasia.